U.S. patent application number 15/922548 was filed with the patent office on 2018-07-19 for injection device for metering a fluid and motor vehicle having such an injection device.
This patent application is currently assigned to CONTINENTAL AUTOMOTIVE GMBH. The applicant listed for this patent is CONTINENTAL AUTOMOTIVE GMBH. Invention is credited to Dejan Jovovic, Anatoliy Lyubar.
Application Number | 20180202404 15/922548 |
Document ID | / |
Family ID | 56738101 |
Filed Date | 2018-07-19 |
United States Patent
Application |
20180202404 |
Kind Code |
A1 |
Jovovic; Dejan ; et
al. |
July 19, 2018 |
INJECTION DEVICE FOR METERING A FLUID AND MOTOR VEHICLE HAVING SUCH
AN INJECTION DEVICE
Abstract
An injection device for metering a fluid, having the following:
a valve, which has a valve needle and a valve seat; a nozzle shaft,
which surrounds the valve needle and which holds a volume of the
fluid; and an inlet chamber, which adjoins the nozzle shaft on the
side of the nozzle shaft facing away from the valve and which has a
flow connection to the nozzle shaft. The injection device has at
least one compressible volume compensation element, which is filled
with a gas and which, within the injection device, is in contact
with the fluid.
Inventors: |
Jovovic; Dejan; (Regensburg,
DE) ; Lyubar; Anatoliy; (Wolfsegg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CONTINENTAL AUTOMOTIVE GMBH |
Hannover |
|
DE |
|
|
Assignee: |
CONTINENTAL AUTOMOTIVE GMBH
Hannover
DE
|
Family ID: |
56738101 |
Appl. No.: |
15/922548 |
Filed: |
March 15, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2016/069022 |
Aug 10, 2016 |
|
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15922548 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N 3/2066 20130101;
F02M 21/0263 20130101; F01N 2610/02 20130101; Y02T 10/12 20130101;
Y02T 10/24 20130101; F02M 21/0251 20130101; F02M 61/167 20130101;
Y02T 10/30 20130101; F02M 51/0682 20130101; Y02T 10/32 20130101;
F01N 2610/1453 20130101; Y02A 50/2325 20180101; F01N 2610/1486
20130101; Y02A 50/20 20180101; F01N 2610/146 20130101 |
International
Class: |
F02M 61/16 20060101
F02M061/16; F01N 3/20 20060101 F01N003/20; F02M 51/06 20060101
F02M051/06; F02M 21/02 20060101 F02M021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 15, 2015 |
DE |
10 2015 217 673.8 |
Claims
1. An injection device for metering a fluid, comprising: a valve,
which has a valve needle and a valve seat; a nozzle shaft, which
surrounds the valve needle and which holds a volume of the fluid;
an inlet chamber, which adjoins the nozzle shaft on the side of the
nozzle shaft facing away from the valve and which has a flow
connection to the nozzle shaft; at least one compressible volume
compensation element, which is filled with a gas; and a wall
region, the wall region being part of the at least one compressible
volume compensation element, the wall region being composed of a
martensitically hardened steel; wherein the at least one
compressible volume compensation element is in contact with the
fluid.
2. The injection device of claim 1, the at least one volume
compensation element further comprising regions composed of a
flexible, porous plastic, wherein the pores of the plastic are
filled with a gas.
3. The injection device of claim 1, the at least one volume
compensation element further comprising an inlay, wherein the inlay
is arranged in the interior of the injection device in such a way
that the inlay is surrounded substantially completely by the
fluid.
4. The injection device of claim 1, the at least one volume
compensation element further comprising a lining of a wall of the
nozzle shaft.
5. The injection device of claim 1, the at least one volume
compensation element further comprising a lining of the inlet
chamber.
6. The injection device of claim 1, wherein the at least one volume
compensation element is arranged in the inlet chamber of the
injection device.
7. The injection device of claim 1, wherein the volume compensation
element is arranged in the nozzle shaft of the injection
device.
8. The injection device as claimed in claim 1, the valve needle
further comprising: a gas-filled cavity within the interior of the
valve needle; wherein the valve needle is formed from
martensitically hardened steel.
9. The injection device of claim 1, wherein the injection device is
used for a urea solution in an exhaust gas aftertreatment
system.
10. The injection device of claim 9, wherein the injection device
is used as part of a motor vehicle.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of PCT Application
PCT/EP2016/069022, filed Aug. 10, 2016, which claims priority to
German Patent Application 10 2015 217 673.8, filed Sep. 15, 2015.
The disclosures of the above applications are incorporated herein
by reference.
FIELD OF THE INVENTION
[0002] The present disclosure relates to an injection device for
metering a fluid. In particular, it relates to an injection device
for metering a urea solution in an exhaust gas aftertreatment
system of a motor vehicle. It furthermore relates to a motor
vehicle having such an injection device.
BACKGROUND OF THE INVENTION
[0003] An injection device for metering a liquid or gaseous medium,
in particular a urea solution, is known from DE 2008 041 544 A1,
for example. With such injection devices, there is the problem that
the fluid may freeze and destroy the injection device by the
associated expansion in its volume. For example, urea solution
freezes at a temperature of -7.degree. C.
[0004] Hitherto, the procedure has been, for example, to spray all
the liquid out of the injection device when switching off the
engine in an attempt to largely remove the urea solution from the
injection device so as to prevent damage to the injection device
due to an expansion in volume when the solution freezes. However,
it is not possible to spray all the liquid out of the injection
device in all cases and this is also not necessarily desired.
SUMMARY OF THE INVENTION
[0005] It is an object of the present invention to specify an
injection device for metering a fluid with which the risk of
destruction by freezing fluid is reduced.
[0006] This object is achieved by the subject matter of patent
claim 1. Advantageous configurations are the subject matter of the
dependent claims.
[0007] According to a first aspect of the invention, an injection
device for metering a fluid is specified. According to another
aspect, a motor vehicle having the injection device described is
specified.
[0008] The injection device has a valve, which has a valve needle
and a valve seat, and a nozzle shaft, which surrounds the valve
needle and which holds a volume of the fluid. The injection device
furthermore has an inlet chamber, which adjoins the nozzle shaft on
the side of the nozzle shaft facing away from the valve and which
has a flow connection to the nozzle shaft. The injection device has
at least one compressible volume compensation element, which is
filled with a gas and which, within the injection device, is in
contact with the fluid. The valve shaft is preferably formed by a
valve body of the injection device and/or by the at least one
volume compensation element. In one embodiment, the injection
device is a fluid injection valve.
[0009] Here and below, a volume compensation element in contact
with the fluid is understood to mean a volume compensation element
on which forces can be exerted by the fluid. In particular, the
volume compensation element is designed and arranged in such a way
that forces are exerted on the volume compensation element owing to
the increase in volume if the fluid freezes. Since the volume
compensation element is compressible, it can compensate for an
expansion in the volume of the fluid. In particular, compensation
is accomplished by compression of the gas with which the volume
compensation element is filled. In particular, the volume
compensation element is designed in such a way that the volume
thereof decreases by a value which corresponds to 3.5% or more,
preferably by 5% or more, in particular between 5% and 9%,
inclusive, of the volume of the valve shaft when a urea solution
filling the valve shaft freezes. Here, the volume of the valve
shaft is understood to mean the fluid volume which the valve shaft
holds during the operation of the injection device for injecting
the fluid.
[0010] As a result, the risk of damage to the injection device is
particularly low. In particular, the volume compensation element is
in this way designed to compensate for the increase in volume of
the urea solution when said solution freezes. This is about 7%, for
example.
[0011] According to one embodiment, at least one volume
compensation element has a wall region composed of a
martensitically hardened steel. In this case, the wall region can
completely or partially surround the gas filling. The use of a
martensitically hardened steel for the volume compensation element
has the advantage that, in the case of this material, the
transition between elastic and plastic behavior occurs at very high
forces, and therefore the material has a high strength at the same
time as high toughness.
[0012] Martensitically hardened steels are also referred to as
"maraging steels" (a portmanteau word formed from "martensite" and
"aging"). They generally have a very low carbon content and are
alloyed with a high proportion of nickel and can contain other
alloying elements such as cobalt, molybdenum, aluminum, copper,
niobium and/or titanium, which promote the formation of the
martensite phase in the iron, given suitable heat treatment.
Admittedly, conventional maraging steels have a relatively high
nickel content, typically greater than 8% by weight and, in some
cases, more than 12% by weight. However, there are also new high
performance steels which are likewise included among maraging
steels and have a nickel content of just 2-3% by weight and a
manganese content of 9-12% by weight. Such maraging steels are also
suitable for the wall region of the volume compensation
element.
[0013] In this embodiment of the volume compensation element, it is
possible, in particular, to envisage that a strip or sheet composed
of martensitically hardened steel is welded to an inner wall of the
nozzle shaft or to the inlet chamber in such a way that a
gas-filled pocket forming the volume compensation element is formed
between the inner wall and the sheet or strip of martensitically
hardened steel. In the case of such a design, expanding fluid acts
on the wall region composed of martensitically hardened steel as it
freezes, the steel, for its part, acting on the gas enclosed behind
said wall. The gas-filled pocket is thus compressed.
[0014] This embodiment has the advantage that the volume
compensation element can be arranged selectively where the risk of
damage to the injection device from stagnant fluid is particularly
high.
[0015] According to another embodiment, the at least one volume
compensation element has regions composed of a flexible, porous
plastic, wherein the pores of the plastic are filled with a gas. In
this embodiment, a volume compensation element which can be used in
a flexible manner and which can be arranged selectively where
damage due to expanding fluid would be expected is likewise made
available. Moreover, the use of a flexible, porous plastic has the
advantage that the volume compensation element is relatively light
and cannot leak as easily, which would result in a loss of
compressibility.
[0016] In one embodiment, the at least one volume compensation
element is designed as an inlay and is arranged in the interior of
the injection device in such a way that it is surrounded
substantially completely by the fluid.
[0017] Here and below, an inlay is understood to mean a separate
element which already in itself forms the volume compensation
element and is arranged in a chamber of the injection device. The
inlay is surrounded substantially completely by the fluid when it
is surrounded by fluid over the great majority of its surface.
Small surface areas--e.g. 25% or less, preferably 10% or less, in
particular 5% or less--can be used to suspend or secure the inlay
in the chamber, for example, ensuring that it does not come into
contact with the fluid.
[0018] This embodiment has the advantage that a large surface of
the volume compensation element is available for the action of
forces exerted by the fluid.
[0019] In an alternative embodiment, the at least one volume
compensation element is designed as a lining of a wall of the
nozzle shaft and/or of the inlet chamber. In this case, the volume
compensation element can be designed, for example, as a wall lining
composed of flexible, porous plastic or as a gas-filled pocket
having a wall region composed of martensitically hardened
steel.
[0020] This embodiment has the advantage that it is a relatively
simple matter to secure the volume compensation element within the
injection device.
[0021] In particular, the volume compensation element can be
arranged in an inlet chamber (or inlet tube) of the injection
device. As an alternative or in addition, it can also be arranged
in the nozzle shaft of the injection device.
[0022] On the one hand, the installation space is available in
these regions and, on the other hand, these are also the regions in
which the fluid is stagnant and damage can be expected in the case
of freezing.
[0023] According to one embodiment, the valve needle is formed from
martensitically hardened steel and has a gas-filled cavity within
its interior. In this embodiment, the valve needle itself forms the
volume compensation element or one of the volume compensation
elements. By virtue of its deformable walls and the gas-filled
cavity, it is compressible.
[0024] This embodiment has the advantage that a relatively large
volume compensation element can be made available without the need
to create additional installation space within the injection
device.
[0025] In particular, the injection device is designed as an
injection device for a urea solution in an exhaust gas
aftertreatment system since, owing to the freezing point of urea
solution of -7.degree. C., such injection devices must be protected
appropriately against destruction by the expansion in volume of the
urea.
[0026] According to another aspect of the invention, it is also
possible to form parts of the injection device from martensitically
hardened steel in order to achieve a particular resistance. For
example, a nozzle plate which, in particular, has the valve seat
and/or at least one nozzle of the injection device, can be formed
from martensitically hardened steel. As an alternative or in
addition, the valve body can be formed from martensitically
hardened steel--in particular at least in the region of the nozzle
shaft. In this and other embodiments, the nozzle shaft is
preferably arranged upstream of the nozzle plate and, in
particular, can adjoin said nozzle plate. The nozzle shaft and the
nozzle plate can be produced integrally--that is to say, in
particular, from one and the same workpiece--or manufactured
separately. This can be combined with the volume compensation
elements described or can be used in isolation to obtain a better
strength for the injection device.
[0027] Further areas of applicability of the present invention will
become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description and specific
examples, while indicating the preferred embodiment of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Further advantages and advantageous embodiments and
developments of the injection device will become apparent from the
following exemplary embodiments described in greater detail with
reference to figures.
[0029] FIG. 1 shows diagrammatically a section through an injection
device according to a first exemplary embodiment of an
invention;
[0030] FIG. 2 shows diagrammatically a detail of the injection
device shown in FIG. 1;
[0031] FIG. 3 shows diagrammatically a further detail of the
injection device shown in FIG. 1;
[0032] FIG. 4 shows details of embodiments of the volume
compensation elements of the injection device shown in FIG. 1;
[0033] FIG. 5 shows diagrammatically a section through an injection
device according to a second exemplary embodiment of the invention;
and
[0034] FIG. 6 shows diagrammatically a section through an injection
device according to a third exemplary embodiment of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] The following description of the preferred embodiment(s) is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses.
[0036] FIG. 1 shows an injection device 1 in accordance with a
first exemplary embodiment of the invention, which is designed as
an injection device for a urea solution in a system for exhaust gas
aftertreatment in a motor vehicle.
[0037] The injection device 1 has a valve 3, which has a valve
needle 5, a tip 7 designed as a ball, and a valve seat 9. When
closed, the tip 7 is pressed onto the valve seat 9 by the force of
a spring 30 and thus closes the nozzle 11. The valve seat 9 and the
nozzle 11 are contained in a nozzle plate of the injection device
1, which is designed as an injection valve. A valve housing 13
surrounds the valve 3 and the nozzle shaft 15, which is formed as a
cavity within the valve housing 13 and is filled with urea solution
during operation. An opening 17 in the valve needle 5, which is of
hollow design, allows urea solution to cross into the nozzle shaft
15.
[0038] An inlet chamber 19, which is formed by the inlet tube 18
and has a flow connection to the nozzle shaft 15, adjoins the
nozzle shaft on the side of the nozzle shaft 15 facing away from
the valve. Arranged in the inlet chamber 19 is a filter 29 for the
fluid, by means of the positioning of which the preload of the
spring 30 can be adjusted.
[0039] During operation, the inlet chamber 19 and the nozzle shaft
15 are filled with the fluid to be injected--urea solution in the
exemplary embodiment under consideration. In order to allow
injection of urea solution through the nozzle 11, the injection
device 1 has an electromagnetic actuation device.
[0040] The electromagnetic actuation device has a coil 21, an
armature 23, a pole piece 25 and a nonmagnetic sleeve 27, which is
press-fitted onto one end of the pole piece 25. The armature 23 is
movable relative to the valve body 13 in the longitudinal direction
of the injection device 1 and takes along the valve needle 5, which
opens the nozzle 11 when moved in a direction away from the valve
seat 9 and allows urea solution to emerge through the nozzle
11.
[0041] The injection device 1 has gas-filled compressible volume
compensation elements 33, which allow compensation of a volume
increase of the urea solution in the event of freezing and thus
prevent damage to the injection device 1. In the first embodiment
shown, a first volume compensation element 33 is arranged in the
region of the nozzle shaft 15 and a second volume compensation
element 33 is arranged in the region of the inlet chamber. In the
embodiment shown, both volume compensation elements 33 are designed
as wall linings.
[0042] The volume compensation elements 33 according to this first
embodiment are shown in detail in FIGS. 2 and 3. For the sake of
simplicity, FIGS. 2, 3, 5 and 6 show only the half of the injection
device 1 above the axis of symmetry 34.
[0043] The volume compensation elements 33 each have a wall 35,
which is formed by a thin sheet or strip composed of a
martensitically hardened steel. The wall 35 is welded to the valve
housing 13 or the inlet tube 18 in such a way that a gas-filled
cavity 37 is formed between the wall 35 and the valve housing 13 or
the inlet tubing 18. In particular, the gas-filled cavity is filled
with air. The surface of the nozzle shaft 15 which defines the
fluid-filled cavity and which is in contact with the fluid is thus
formed by a surface of the volume compensation element 33 welded to
the valve housing 13 and, where applicable, by regions of an inner
circumferential surface of the valve body 13 which are uncovered by
the volume compensation element 33.
[0044] If the urea solution freezes and there is an associated
increase in volume, the urea solution exerts a force on the wall 35
of the volume compensation elements 33. Owing to this force, the
air in the gas-filled cavity 37 is compressed and the wall 35
undergoes deformation during this process. No additional force is
exerted on other components of the injection device 1, e.g. on the
valve housing 13 or the inlet tube 18, or a force exerted thereon
is greatly reduced, by virtue of the fact that the volume
compensation elements 33 compensate for the majority of the
increase in volume or even the entire increase in volume of the
urea solution. Thus, the loading of the injection device 1 due to
freezing fluid is greatly reduced and its service life is thus
increased.
[0045] FIG. 4 shows different embodiments of the volume
compensation elements 33 shown in FIGS. 1 to 3. While the wall 35
is largely parallel to the inner wall of the valve housing 13 and
of the inlet tube 18 in the upper illustration in FIG. 4, the wall
35 in the lower illustration in FIG. 4 has an undulating shape in
section. This enlarges its surface area and increases its
deformability.
[0046] FIG. 5 shows an injection device 1 for a liquid urea
solution according to a second exemplary embodiment of the
invention. This differs from that shown in FIGS. 1 to 3 in that the
volume compensation element 33 is formed by the valve needle 5
itself. In this embodiment, the valve needle 5 is of closed and
internally hollow design. Since it is closed, it is not filled with
urea solution during operation. On the contrary, it has a solid
main body 45, which can be composed of martensitically hardened
steel, for example, and a compressible body 47, which is arranged
around the main body and connected thereto and which forms the
volume compensation element 33. As already described in connection
with other embodiments, the compressible body 47 can be formed from
porous plastic or can have a wall 35 with a gas-filled cavity 39
behind it.
[0047] In the embodiment shown, the martensitically hardened steel
has a composition of 8% by weight of nickel, 1% by weight of
molybdenum, 13% by weight of chromium, a maximum of 0.5% by weight
of beryllium, with the remainder being iron. This material has very
good deformability, good spring properties and good corrosion
resistance. As has been found, it is very suitable for the
formation of volume compensation elements 33 by virtue of these
properties.
[0048] Since, in this embodiment, the valve needle 5 is sealed and
not filled with urea solution, an opening 41 for the urea solution
from the inlet chamber 19 into the nozzle shaft 15 is provided
above the valve needle 5, in the region of the armature 23.
[0049] FIG. 6 shows an injection device 1 according to a third
embodiment of the invention. This differs from the other
embodiments in that the volume compensation element 33 is formed by
an inlay 43 arranged within the inlet chamber 19. The inlay 43 is
designed as a compressible body, e.g. as a plastic body composed of
a flexible plastic with gas-filled pores therein or as a body with
a metal wall, which surrounds a gas-filled cavity. Steel can be
used as a material for the metal wall, for example. In addition to
maraging steels, stainless steels are also suitable.
[0050] The inlay 43 is substantially surrounded by urea solution
since it is arranged centrally in the inlet chamber 19. In the
embodiment shown in FIG. 6, it is arranged along the axis of
symmetry 34 of the injection device 1. The inlay 43 is fixed in the
inlet chamber 19 in this position, in which it offers a large
surface to the fluid. The fastening, which is not shown in FIG. 6,
can be accomplished by clipping, for example, that is to say, in
particular, by fastening by means of a spring clip.
[0051] If the urea solution freezes, forces act on the inlay 43
from all sides and compress it so as to compensate the increase in
volume of the urea solution, thus preventing damage to the
injection device 1.
[0052] The description of the invention is merely exemplary in
nature and, thus, variations that do not depart from the gist of
the invention are intended to be within the scope of the invention.
Such variations are not to be regarded as a departure from the
spirit and scope of the invention.
* * * * *